Robots are becoming increasingly sophisticated with regards to the complexity of the tasks they can perform. The increased sophistication results from improved robot functionality as well as improved automation that leverages the functionality to implement more complex tasks. As a result, robots can better assist humans by supplementing humans in certain capacities and replacing humans in other capacities more suited or more efficient for the robot to perform.
One particular area where robotic automation is used with greater sophistication and functionality is in order fulfillment and inventory control. Large retailers, warehouse operators, or distributors, like Amazon.com®, rely on robots to assist human workers in fulfilling orders.
Such retailers, warehouse operators, or distributors house their inventory in one or more distribution sites. FIG. 1 conceptually illustrates a distribution site. The distribution site is typically a large enclosed space with shelves 120 located throughout the space. The shelves can be several feet or stories high with several rows or racks. On each row or rack are several bins 130 that store quantities of the same item. In some cases, the items are stacked directly on the shelf rows or racks without the bins.
With partial robotic automation, rather than have a human worker traverse the warehouse in order to locate each item of a customer order, robots perform the retrieval operation for the human, thereby freeing the human to focus on fulfilling and ensuring correctness of the order. Specifically, the warehouse management/control system (WMS/WCS) receives the order and identifies a location within the distribution site where a human will fulfill the order. The order, along with the human's position for that order, are passed to one or more robots. The robots navigate the distribution site to locate the shelves where each order item is located. The robots lift the shelves containing one or more items of the customer order and deliver those shelves to the human's position. The human then sorts through each delivered shelf to obtain the one or more order items contained within the shelf. The human scans the obtained items and enters the obtained items into a customer order box to fulfill the order one item at a time. The human dismisses each robot when there are no more items left to pull for the customer order from the shelf delivered by the robot. Consequently, the robot returns the shelf to its previous location within the distribution site. The next robot then delivers the next shelf containing additional customer order items. This continues until the human has fulfilled the entire order.
By delivering the shelves containing the ordered items to the human location rather than have the human go to the individual shelf locations, the humans, and in turn, overall order fulfillment, become more efficient. However, such automation systems, in many cases, require a complete overhaul of the distribution site. The overhaul involves replacing the shelving with specialized shelving that the robots can lift and move within the distribution site. A more efficient system uses existing shelving, and works alongside existing manual labor, in order to allow distribution site operators to scale automation gradually until eventually all human involvement from order fulfillment and inventory management is eliminated.
Another shortcoming of prior art systems that prevents full automation is the limited functionality of prior art robots. Robots of the prior art are limited to moving only along an x-y spatial plane. This allows them to retrieve the shelves for the human, but prevents them from accessing the shelf rows and retrieving individual items from the shelves. To promote further automation, there is a need to enable intelligent robotic movement along a z spatial plane in addition to movements along the x and y spatial planes.